Three-dimensional modeling method for narrow-size hole inner cavity

Abstract

The invention relates to a three-dimensional modeling method for an inner cavity of a narrow-size hole, and the method comprises the steps: carrying out the three-dimensional modeling of the inner wall of a hole with a centimeter-level (10-90mm) diameter, enabling a miniature optical monocular camera to stretch into the hole, rapidly obtaining a high-definition picture of the inner wall of the hole, and generating a high-precision live-action three-dimensional model through the picture; a handheld laser scanner is used for scanning the surface of a narrow hole in different directions, three-dimensional modeling of the outside of the hole is completed through software processing, a three-dimensional model in the hole is spliced and fused to a three-dimensional point cloud model of the outer surface of the hole through software, and then measurement and analysis are conducted on the three-dimensional point cloud model. And finally, size calibration is carried out on the live-action three-dimensional model, and the object size of the hole three-dimensional model is precisely reduced in an equal ratio. And a very convenient method is provided for research and observation of the internal morphology of the narrow hole and measurement of geometric quantities such as hole section and depth.

Description

Technical Field

[0001] This invention belongs to the field of 3D modeling technology, specifically relating to a 3D modeling method for the internal cavity of a small-sized hole. Background Technology

[0002] For scenarios such as holes and pipes with diameters on the order of centimeters, in order to intuitively and three-dimensionally view the internal scene and specifically assess the internal state, it is necessary to reconstruct the internal cavity of the narrow-sized hole in three dimensions, so as to display the actual condition of the internal cavity in three dimensions, and then to accurately measure and analyze the internal cavity, which serves as an important basis for evaluating the three-dimensional visualization of the internal cavity structure.

[0003] In existing technologies, 3D modeling of small holes (with diameters on the order of centimeters) typically involves either filling the hole with resin, allowing it to cure, and then removing the hole to obtain a scale model, or sectioning the hole, scanning the internal structure in 3D, and then measuring it. These traditional methods are difficult and inefficient in practice. For small holes, they can only measure the size and location of the opening, failing to acquire data about the internal cavity. Furthermore, due to the different measurement methods used, internal and external information cannot be fused to form a complete target model.

[0004] Furthermore, it is impossible to effectively collect data inside the holes. Even when using a crawling camera, the angle and structure of the hole limit the ability to obtain a complete model through the narrow opening. Due to the shortcomings of traditional methods, there is an urgent need for a 3D modeling method for the interior of narrow holes to achieve 3D reconstruction of these cavities. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems. This application proposes a three-dimensional modeling method for the internal cavity of narrow-sized holes. By using a handheld laser scanner and a monocular camera in combination, the method solves the problem of three-dimensional reconstruction of the internal cavity of narrow-sized holes, restores the three-dimensional contour of the narrow holes proportionally, and finally generates three-dimensional point cloud or surface data that is commonly used in the industry.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a three-dimensional modeling method for the internal cavity of a small-sized hole, comprising the following steps: S1. Use a handheld laser scanner to scan the outer surface of the hole scene to ensure that the surface of the hole opening can be scanned and obtain the hole opening model; S2. Optimize the obtained hole model to obtain a 3D point cloud model of the outer surface of the hole scene; S3. Insert the monocular camera into the hole scene through the connection of the adaptive cable. The other end of the adaptive cable is connected to the control terminal to acquire the image captured by the monocular camera. S4. Import the image obtained in step S3 into the Context Capture modeling software, perform three-dimensional reconstruction, and obtain a three-dimensional model of the hole's interior. S5. Import the obtained 3D model of the hole scene into Geomagic software, and use the 3D model registration and fusion method to stitch and fuse the 3D model inside the hole into the 3D point cloud model obtained in step S2. S6. Use measurement software to measure and analyze the fused 3D point cloud model.

[0007] Furthermore: In step S1, the orientation of the hole scene includes: the front, back, left, right and diagonal orientations of the outer surface of the hole scene, the top and bottom orientations, and the positions above and below the hole.

[0008] Furthermore: The steps for using a monocular camera to acquire images in step S3 are as follows: 1) Connect the two ends of the adaptive cable to the monocular camera and the control terminal, respectively; 2) Insert the monocular camera end into the scene with the hole; 3) Control the monocular camera through the control terminal to complete omnidirectional image acquisition.

[0009] Furthermore: the monocular camera, adaptive cable, and control terminal constitute a monocular image acquisition system for acquiring the texture of the inner wall of the hole scene.

[0010] Furthermore: the resolution of the monocular camera is 1280×720 pixels, and the image acquisition speed of the monocular camera is 3 frames / second.

[0011] Furthermore: In step S4, the specific steps of 3D reconstruction are as follows: 1) First, based on the initial internal parameters of the monocular camera, establish the image space transformation relationship of the monocular camera; analyze and extract the image features of the hole sidewall, and perform image matching and localization; 2) By calculating and determining the real spatial relationship of the monocular camera and the three-dimensional shape between the holes, the sparse point cloud of the holes is extracted; then the point cloud is densified, point cloud triangular patches are established, and the entire inner wall of the hole is modeled in three dimensions, textured, and output to complete the offline three-dimensional reconstruction.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a handheld laser scanner to scan the surface of a narrow hole from different angles, and then processes the data using software to create a 3D model of the hole's exterior. The monocular image acquisition system is suitable for 3D reconstruction of narrow holes of various sizes and angles (horizontal, vertical, tilted, etc.), acquiring images of the hole's inner wall without requiring high-precision hardware. Based on pre-determined initial intrinsic and extrinsic parameters of the monocular camera, and using image feature points and algorithmic correction, relevant measurement data is quickly obtained. The monocular image acquisition system is suitable for irregular hole diameters down to the centimeter level, acquiring images of the hole's inner wall and creating a 3D model of the narrow hole based on the image data. The Geomagic post-processing software is then used to register, stitch, and fuse the hole model, enabling rapid geometric measurement. The equipment used in this invention has low energy consumption, requiring no high-power power supply, making it suitable for field operations. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only for more clearly illustrating the technical solutions in the embodiments of the present invention or the prior art. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the overall structure of the monocular image acquisition system of the present invention; Figure 2 This is a scene demonstration diagram of the present invention used for three-dimensional modeling of the inner cavity of a narrow hole; In the image: 1-Monocular camera, 2-Adaptive cable, 3-Control terminal, 4-Handheld laser scanner, 5-Hole scene. Detailed Implementation

[0015] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments. However, the embodiments are only for illustration and are not intended to limit the present invention.

[0016] like Figures 1-2 The method shown here for three-dimensional modeling of the internal cavity of a small-sized hole includes the following steps: After the sweep test: A handheld laser scanner 4 was used to scan the surface of the narrow hole opening (i.e., hole scene 5) from different angles to ensure that the surface of the hole opening in hole scene 5 could be scanned by the handheld laser scanner 4, to obtain the hole opening model, and to optimize it to obtain a three-dimensional point cloud model of the outer surface of the hole opening.

[0017] The working steps of a monocular image acquisition system are as follows: Take pictures on site; The image is reconstructed in three dimensions to obtain measurement data.

[0018] The process is as follows: power on and check the equipment (control terminal, monocular camera) → connect and set parameters → insert into the hole to acquire images → perform 3D reconstruction of the images → analyze measurement data.

[0019] Priority: The monocular image acquisition system consists of an adaptive cable 2 and a monocular camera 1 and a control terminal 3 connected to both ends, as follows: Figure 1 As shown.

[0020] Specifically: The specific steps for obtaining images on-site are as follows: The monocular camera 1 uses a small-sized miniature optical camera and is equipped with a short-focal-length lens to capture images covering the inner wall surface. By advancing from head to tail, it ensures that the images inside the hole scene 5 can be collected from all directions and is suitable for different angles: horizontal, vertical, tilt, etc.

[0021] Preferably, the monocular camera 1 has a resolution of 1280×720 pixels and a shooting frame rate of 3 frames / second to ensure that a sufficient number of images can be acquired and to guarantee a large overlap rate between images, which is convenient for image analysis.

[0022] Before the monocular camera 1 enters the hole scene 5, the system powers on for a self-test to confirm its working status.

[0023] During operation, the position of the monocular camera 1 is confirmed by the scale on the adaptive cable 2 and the real-time video. Any abnormalities in the hole scene 5 can be judged by the operator in real time. After reaching the bottom of the hole scene 5, the monocular camera 1 is controlled by the control terminal 3 - tablet to take pictures. The monocular camera 1 is gradually moved backward along the hole scene 5 by the adaptive cable 2 to take pictures. After reaching the hole of the hole scene 5, the TF card is taken out to copy the image.

[0024] II. Image 3D reconstruction to obtain measurement data Import the image into Context Capture software for 3D reconstruction to obtain a 3D model of the inside of the hole.

[0025] Specifically: the 3D reconstruction process is based on the pre-calibrated initial intrinsic and extrinsic parameters of the monocular camera 1, establishes the initial image spatial transformation relationship (eigenvalue matrix and fundamental matrix), analyzes and extracts the features of the inner wall image, and performs image matching and localization; After calculation, the true spatial relationships and 3D morphology of the hole were determined using monocular camera 1. The sparse point cloud of the hole was extracted, and the point cloud was densified to create point cloud triangular patches. This completed the 3D modeling and texture mapping of the inner wall of the entire hole scene 5. 3D data files in ply, obj, and stl formats were output for offline 3D reconstruction.

[0026] The obtained 3D model of the interior of the hole scene 5 was imported into Geomagic software. Using the 3D model registration and fusion method, the 3D model inside the hole scene 5 was stitched and fused to the 3D point cloud model on the outer surface of the hole scene 5. Finally, the fused 3D point cloud model was measured and analyzed using measurement software.

[0027] The three-dimensional modeling method of the present invention can quickly acquire and reconstruct a three-dimensional model of a narrow hole, and fuse it with the external scanning data of the hole to construct an overall three-dimensional model of the inside and outside. Through the processing, analysis and calculation of the three-dimensional model, the geometric quantities of the cavity of the narrow hole can be quickly measured.

[0028] All content not described in detail in this invention is prior art.

[0029] The above description is merely a preferred embodiment of the present invention and is not limited to the description in the specification and embodiments. Therefore, all equivalent changes or modifications made to the structure, features, and principles described in the claims of this invention should be included within the scope of this patent application.

Claims

1. A three-dimensional modeling method for the internal cavity of a small-sized hole, characterized in that: Includes the following steps: S1. Use a handheld laser scanner to scan the outer surface of the hole scene to ensure that the surface of the hole opening can be scanned and obtain the hole opening model; S2. Optimize the obtained hole model to obtain a 3D point cloud model of the outer surface of the hole scene; S3. Insert the monocular camera into the hole scene through the connection of the adaptive cable. The other end of the adaptive cable is connected to the control terminal to acquire the image captured by the monocular camera. S4. Import the image obtained in step S3 into the Context Capture modeling software, perform three-dimensional reconstruction, and obtain a three-dimensional model of the hole's interior. S5. Import the obtained 3D model of the hole scene into Geomagic software, and use the 3D model registration and fusion method to stitch and fuse the 3D model inside the hole into the 3D point cloud model obtained in step S2. S6. Use measurement software to measure and analyze the fused 3D point cloud model.

2. The three-dimensional modeling method for the internal cavity of a small-sized hole according to claim 1, characterized in that: In step S1, the orientation of the hole scene includes: the front, back, left, right and diagonal orientations of the outer surface of the hole scene, the top and bottom orientations, and the positions above and below the hole.

3. The three-dimensional modeling method for the internal cavity of a small-sized hole according to claim 1, characterized in that: The steps for using a monocular camera to acquire images in step S3 are as follows: 1) Connect the two ends of the adaptive cable to the monocular camera and the control terminal, respectively; 2) Insert the monocular camera end into the scene with the hole; 3) Control the monocular camera through the control terminal to complete omnidirectional image acquisition.

4. The three-dimensional modeling method for the internal cavity of a small-sized hole according to claim 1, characterized in that: The monocular camera, adaptive cable, and control terminal constitute a monocular image acquisition system for acquiring the texture of the inner wall of the hole scene.

5. A three-dimensional modeling method for the internal cavity of a small-sized hole according to claim 4, characterized in that: The monocular camera has a resolution of 1280×720 pixels and an image capture speed of 3 frames per second.

6. A three-dimensional modeling method for the internal cavity of a small-sized hole according to claim 1, characterized in that: In step S4, the specific steps of 3D reconstruction are as follows: 1) First, based on the initial internal parameters of the monocular camera, establish the image space transformation relationship of the monocular camera; analyze and extract the image features of the hole sidewall, and perform image matching and localization; 2) The real spatial relationships of the monocular camera and the three-dimensional morphology between holes are determined by calculation, and the sparse point cloud of holes is extracted. The point cloud is then densified to create point cloud triangular patches. The entire inner wall of the hole is then modeled in 3D, textured, and output as a file, completing the offline 3D reconstruction.

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